How do I revoke an AI assistant's access?

Go to Settings > Security > Active Sessions. Assistants you have connected are listed under Connected agents, with when each was last active. Tap Disconnect on the one you want to remove. It loses access straight away.

"Terminate all other sessions" signs out your other devices. It does not disconnect connected agents, so disconnect each one yourself.

API keys are managed separately in Settings > Developers > API keys.

Payments you already approved cannot be reversed, since blockchain transactions are final.